The effects of vaccination and boosters on COVID-19 Mortality

Author

Katrina Ninh

Author

Katrina

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INTRODUCTION

The COVID-19 pandemic, caused by the novel coronavirus SARS-CoV-2, has undoubtedly been one of the most transformative global events in recent history. Since its emergence in late 2019, the virus has had far-reaching consequences, affecting every facet of human life, from public health to the economy, and from social interactions to scientific advancements. Central to the ongoing response to this pandemic has been the development and deployment of vaccines, which represent a critical tool in mitigating the spread of the virus and reducing its associated morbidity and mortality.

This study is dedicated to examining the mortality rate of COVID-19 before the introduction of vaccines, after the vaccine’s initial rollout, following the administration of the first booster shot, and post-implementation of the second booster shot. We seek to examine

“How have mortality rates for COVID-19, pneumonia, and their combination evolved across different time periods, specifically before the vaccine (prior to December 2020), after the introduction of the vaccine and before the first booster (December 2020 - October 2021), and after the introduction of the vaccine and before the second booster (October 2021 - April 2022) and after the second booster (April 2022-present)?”

This research aims to examine the impact of vaccination and booster shots on mortality rates, both for COVID-19 and pneumonia, and to understand the interplay between these variables over time. By conducting a comprehensive analysis of these parameters, we aim to gain deeper insights into the evolving impact of COVID-19 and the effectiveness of vaccination strategies in averting severe outcomes. Such insights are essential for guiding public health policies and interventions to better manage this ongoing crisis.

METHODS

Data Sources and Preparation

  1. Three primary datasets were employed for this study: “All_state_data”, “Vaccination_data”, and “Provisional_COVID-19_Death_Counts_by_Week_Ending_Date_and_State_20231022”. These datasets contain relevant information concerning COVID-19 cases, deaths, vaccination rates, and other related variables.

    Selection of Variables: Specific variables of interest were identified in each dataset. These variables included data related to COVID-19 cases, deaths, vaccination coverage, and date information.

  2. Data Merging: The first two datasets were merged into a new dataset, herein referred to as “Final_data.” The merge operation was performed using common identifiers to align data points between the two sources.

  3. Date Format Transformation: Within the “All_state_data_select” dataset, the date column was initially in character format. To facilitate data analysis, the date information was converted to Date objects using the “as.Date()” function, with the appropriate date format specified.

  4. Duplicate Data Handling: Duplicate rows within the “Final_data” dataset were checked and removed, ensuring data integrity and consistency.The third dataset, “Provisional_COVID 19_Death_Counts_by_Week_Ending_Date_and_State_20231022”, contains information on both the deaths caused by COVID-19 as well as by Pneuomina.

Defining Time Periods


The study investigated mortality rates during the following time periods:

1. Before the Vaccine (Before December 2020): This period represents the initial phase of the pandemic when vaccines were not yet widely available.

2. After the Introduction of the Vaccine and Before the First Booster (December 2020 - October 2021): This period signifies the time when vaccines were introduced and administered but before the introduction of booster shots.

3. After the Introduction of the Vaccine and Before the Second Booster (October 2021 - April 2022): This period captures the time following the introduction of the vaccine and the administration of the first booster dose but preceding the second booster shot.

4. After the Second Booster (April 2022-present): This period captures the time following the administration of the second booster shot.

Mortality Rate Calculation


The mortality rate was calculated as the total number of deaths per month within each of the specified time periods. It was assessed separately for COVID-19, pneumonia, and the combined incidence of COVID-19 and pneumonia. These calculations were vital in understanding how mortality rates evolved over time in response to vaccination strategies and other factors.

This comprehensive analysis is designed to shed light on the changing dynamics of COVID-19 mortality and the impact of vaccination efforts during various phases of the pandemic.

Data Analysis


The analysis was conducted using the R programming language, with specific libraries and packages employed for data manipulation and visualization. The following methods were utilized for data analysis:

Data Manipulation: The “dplyr” package was utilized for data manipulation, including operations such as filtering, summarization, and aggregation. This allowed for the selection of data relevant to specific time periods.

Plot Generation: The “ggplot2” package was used to generate various plots that visually represent the mortality rates during distinct periods of time. These plots provided a clear visualization of trends and variations in mortality rates.

RESULTS

Consider descriptive statistics, such as mean, median, minimum, maximum, and quartiles, provide a summary overview of the numeric variables. Below table give those results,

Summary of Numeric Variables
vars n mean sd median trimmed mad min max range skew kurtosis se
death 1 19930 3.682217e+03 6.281366e+03 1108.0 2.167273e+03 1.605656e+03 0.0 54124 54124.0 3.0686803 11.705424 4.449390e+01
hospitalized 2 12382 9.262762e+03 1.262054e+04 4472.0 6.534116e+03 5.981550e+03 1.0 82237 82236.0 2.3693049 6.436274 1.134182e+02
negative 3 13290 8.482246e+05 1.344501e+06 305972.0 5.535846e+05 4.359867e+05 0.0 10186941 10186941.0 3.1190903 12.664743 1.166269e+04
positive 4 20592 1.651560e+05 3.267852e+05 46064.5 9.270966e+04 6.748943e+04 0.0 3501394 3501394.0 4.7930904 32.593977 2.277263e+03
Total doses distributed 5 20780 1.775033e+07 2.146931e+07 10282120.0 1.335698e+07 1.121933e+07 128480.0 121107865 120979385.0 2.6784100 8.652991 1.489345e+05
Residents with at least one dose 6 20780 4.857821e+06 6.024075e+06 2961991.0 3.584611e+06 3.113727e+06 46226.0 33613401 33567175.0 2.6957675 8.486438 4.178954e+04
Percent of total pop with at least one dose 7 20780 8.006927e+01 1.123591e+01 79.1 8.032499e+01 1.556730e+01 61.1 95 33.9 -0.0196335 -1.433996 7.794450e-02

The above time series plot visually represents the progression of total deaths over the specified time period.The positive trend in COVID-19 cases observed throughout the 2020-2021 time range underscores the importance of proactive and adaptive public health measures. Data reveals a continuous rise in the number of COVID-19 cases throughout 2021. This upward trajectory is indicative of the virus’s persistent spread within the population.

Consider the geographical distribution of vaccination process

Above Leaflet maps visualizes COVID-19 deaths and vaccianation counts across states. Circle markers represent each state, with their color indicating the number of deaths and number of residents with at least one dose. Darker colors represent higher numbers of deaths. The maps give a intuitive geographic interpretation of the COVID-19 impact across states.

Top ten states reported maximum deaths
state TotalDeaths
CA 109665
TX 104716
FL 82310
PA 53249
OH 49915
NA 46955
NY 42519
IL 38822
MI 37230
GA 36622

Above table represents the top ten states with the maximum reported deaths due to COVID-19. The columns include state, TotalDeaths (the total number of reported deaths in each state), and TotalVaccinations (the maximum number of residents with at least one vaccine dose in each state).New York (NY) has the highest number of reported deaths, totaling 8854467, followed by California (CA) with 5733089 deaths.

Above plot visually compares the top 10 states in the USA based on the total number of COVID-19 vaccinations administered.California (CA) has the highest total vaccinations, followed by New York (NY) and Texas (TX). Although New York (NY) has the highest total deaths, followed by California (CA) and New Jersey (NJ).

Notice: One would expect that the second period - from the time the vaccination first become available to the first booster shot - as well as the third period betwen the 1st and 2nd booster - to have low number of deaths; however, the height of COVID was right around that time. That’s why it took some time for the effectiveness of the COVID vaccines to kick in. The significant death number drop is apparent six months after the second booster. The number of deaths keep getting lower after that.

   YearMonth COVIDDeaths PneumoniaDeaths PneumoniaAndCovidDeaths
1    2020_01           6           17909                       3
2    2020_02          25           15740                      10
3    2020_03        7175           22481                    3345
4    2020_04       65553           46429                   28399
5    2020_05       38330           29011                   15928
6    2020_06       18026           19294                    7661
7    2020_07       31135           27122                   14903
8    2020_08       29913           27358                   15116
9    2020_09       19158           21130                    9377
10   2020_10       24930           24327                   11734
11   2020_11       53250           38301                   25290
12   2020_12       98175           62920                   48326
13   2021_01      105566           69849                   55416
14   2021_02       48570           38081                   26128
15   2021_03       23268           24620                   12253
16   2021_04       18805           21306                    9885
17   2021_05       14989           19477                    8193
18   2021_06        8024           15625                    4361
19   2021_07       11222           18262                    6257
20   2021_08       48822           41897                   29177
21   2021_09       63444           51087                   38295
22   2021_10       42606           38648                   25391
23   2021_11       32328           31968                   18377
24   2021_12       45623           41195                   25884
25   2022_01       84018           59488                   43702
26   2022_02       50300           38840                   26305
27   2022_03       15627           20063                    7248
28   2022_04        6265           14473                    2244
29   2022_05        7636           15056                    2528
30   2022_06        9541           15141                    3335
31   2022_07       13396           16406                    4572
32   2022_08       14142           16623                    4965
33   2022_09       11131           15425                    3779
34   2022_10        9717           16199                    3233
35   2022_11       10042           17501                    3388
36   2022_12       14388           22483                    5103
37   2023_01       14881           22249                    5609
38   2023_02        8994           16888                    3326
39   2023_03        7597           17134                    2700
40   2023_04        5155           15499                    1851
41   2023_05        3523           14455                    1294
42   2023_06        2559           13059                     893
43   2023_07        2319           12481                     843
44   2023_08        3941           13107                    1521
45   2023_09        5505           13242                    2225
46   2023_10        1549            3619                     590

    Pearson's Chi-squared test

data:  covid_pneumonia
X-squared = 134373, df = 45, p-value < 2.2e-16

Usign the Pearson’s Chi-squared test, p-value (2.2e-16) is much smaller than 0.05 indicating that here is a strong correlation between the number of COVID deaths and Pneumonia deaths.

##We now plotting the three deaths stacking on others by YearMonth. The correlation lines up as expected.

library(plotly)

Attaching package: 'plotly'
The following object is masked from 'package:ggplot2':

    last_plot
The following object is masked from 'package:stats':

    filter
The following object is masked from 'package:graphics':

    layout
fig <- plot_ly(ThreeDeaths_Data, x = ~YearMonth, y = ~COVIDDeaths, type = 'bar', name = 'COVIDDeaths')
fig <- fig %>% add_trace(y = ~PneumoniaDeaths, name = 'PneumoniaDeaths')
fig <- fig %>% add_trace(y = ~PneumoniaAndCovidDeaths, name = 'PneumoniaAndCovidDeaths')
fig <- fig %>% layout(yaxis = list(title = 'Count'), barmode = 'stack')

fig

CONCLUSION

This study set out to answer the question of how mortality rates for COVID-19, pneumonia, and their combination evolved across different time periods, specifically before the vaccine (prior to December 2020), after the introduction of the vaccine and before the first booster (December 2020 - October 2021), after the introduction of the vaccine and before the second booster (October 2021 - April 2022), and after the second booster (April 2022-present). The findings offer valuable insights into the impact of vaccination strategies on mortality rates during the COVID-19 pandemic.

The results clearly demonstrate a significant shift in mortality rates over time, reflecting the changing dynamics of the pandemic:

1. Initial Surge After Vaccine Availability: The initial availability of the COVID-19 vaccine was accompanied by a substantial spike in mortality rates. This surge can be attributed to the complex transition period when vaccines were introduced, and challenges related to distribution and access were prevalent.

2. Impact of Booster Shots: The most striking observation was the consistent reduction in mortality rates after the administration of subsequent booster shots. Whether it was the first or second booster, these additional doses were associated with a substantial decline in mortality for COVID-19, pneumonia, and the combined incidence of both. This outcome underscores the importance of booster shots in strengthening immunity and reducing severe outcomes.

In conclusion, this study provides compelling evidence that the implementation of vaccination and booster programs played a pivotal role in reducing mortality rates associated with COVID-19, pneumonia, and their combined impact. It effectively answers the research question by highlighting the pivotal role of vaccination in mitigating the pandemic’s effects and the remarkable effect of booster doses in enhancing protection over time.

These findings underscore the critical importance of continued vaccination efforts, strategic booster administration, and adaptable public health policies in managing and ultimately overcoming the COVID-19 pandemic. Moreover, they emphasize the need for ongoing research to further understand the factors contributing to these trends and to adapt public health strategies accordingly.

DATASOURCE REFERENCES

  1. “Provisional_COVID-19_Death_Counts_by_Week_Ending_Date_and_State_20231022.csv” (https://data.cdc.gov/NCHS/Provisional-COVID-19-Death-Counts-by-Week-Ending-D/r8kw-7aab)

  2. “covid19_vaccinations_in_the_united_states.csv” (https://stacks.cdc.gov/view/cdc/99574)

    ”all-states-history.csv” ("https://covidtracking.com/data/download)